MUC1 and pachyonychia congenita: Although anti-MUC1 antibodies were different between our series (anti-MUC1-647, Novocastra, Newcastle, UK) and the two others (anti-MUC1-FITC, Biomeda, Foster City, CA, USA), which could explain these different identification levels, the difference was probably due to an under-expression of MUC1 by CRC and PC in our study, compared to the two others.